Certain medical treatments often require the use of medications injected intravenously, or subcutaneously, into the patient. These medications often have standard dosage amounts, tailored to fit the individual needs of different patients. Hospitals have a particularly high use of syringe-administered medications, requiring a substantial number of syringes to be filled daily, to meet their demands.
Typically, hospitals employ their pharmacy technicians or nurses to fill syringes. Pharmaceutical medications are purchased in large source containers that are then transferred to syringes or target containers. To fill a syringe, a technician must position the syringe by either inserting the syringe needle into the source container, or attach the syringe nozzle to a sterile catheter tubing that can deliver the desired medication. Once the syringe is in position, the plunger is directed forwards or backwards, keeping the syringe unit still, to avoid effecting the integrity of the needle or source container. Smaller source bottle containers, i.e., vials, may require the injection of air into the container before the substance is withdrawn.
The typical manual syringe filling procedure places a significant level of stress on the arms, wrists and fingers of the technicians. The stress is exaggerated, due to the repetitious and forceful movements of the wrist and fingers, reduced blood flow to the hands due to static muscle flexing of the upper arms, and the forceful grasping of the syringe during the filling and dispensing process. This repetitive strain to the musculoskeletal system can lead to cumulative trauma disorders like tendinitis and carpal tunnel syndrome. To avoid such physical problems, the stress involved in the filling and dispensing of medications must be reduced.
The type of substance, and/or the size of the syringe being filled, can vary the difficulty of the filling process. Syringes that have a volume capacity of more than twenty cubic centimeters are difficult to fill, due to the amount of fluid that they contain. A continuous pull on the plunger creates the necessary partial vacuum, so that normal atmospheric pressure can force the liquid through the syringe needle or nozzle into the syringe cavity. The amount of physical effort, and length of sustained pull on the plunger, increases when the substance is a dense liquid solution exhibiting a high level of viscosity.
Syringe filling must be a precise process, to gain the proper benefits. Errors in filling syringes can result in problems for the target patient. If the amount of medication administered is not the proper dosage, the patient suffers, and the medical care provider can be held liable for the error. Since issues of human health and recuperation often depend on whether the patient receives the proper amount of medication, the need for equipment that reduces stress on the technician filling the syringes, and reduces the likelihood of error in the filling process, is of extreme importance.
Prior mechanisms have been introduced as precision measuring devices, which can measure out multiple dosage units, generally from a pumping syringe. Some have incorporated adjustable systems into them, which allow a user to vary the dosage amount dispensed. While there may be some usefulness for the prior apparatus in dispensing vaccines and other types of standard dosage medications, the operation and use of these apparatuses are cumbersome when the intended use is for individual syringes with varied dosage amounts rather than a uniform metered amount. The prior apparatuses have limited mobility, curtailing their ability to deal with a variety of source containers and with the dislodging of air bubbles within a syringe.
This invention is portable, and fits within the manual syringe filling process currently in use at hospitals around the country, and taught at leading medical institutions. Portability and ergonomic design reduce musculoskeletal stress on technicians, promoting enhanced productivity and higher accuracy.
U.S. Pat. No. 2,966,175 (D. F. Hyde) reveals a pump system with a liquid delivery apparatus. A motor pulls on the plunger of a large syringe, causing the syringe to fill with the desired liquid substance. Once the syringe is filled, it is ready for delivery of the liquid. The intended use of this apparatus was to meter out specific amounts of substances into other target containers. The syringe was not intended for removal from the apparatus, nor did it have the capability for various positions. It was simply a pumping mechanism, when filled with the liquid medication.
In U.S. Pat. No. 3,935,883, (Stach et al) a syringe was again used as the pumping unit, in which the plunger was urged toward the rear of the syringe, and a fluid substance was drawn into the syringe barrel. The same motor would then urge the plunger toward the front of the syringe, pumping or forcing the fluid substance out of the syringe. Valves in a supply and delivery tube directed the liquid substance into the syringe for filling, and into a target syringe upon the pumping cycle. This apparatus was limited to the use of dispensing a uniform dosage, as would be needed for vaccines. The unit was not portable, or hand held, and all medications had to be positioned in relationship to the pumping syringe.
U.S. Pat. No. 4,155,490 (Glenn) provided a syringe and a mechanized frame that urged a syringe plunger back and forth in the syringe. This apparatus was cumbersome, and had no realistic means of being held and operated unless on a stable surface. The syringe was secured to a frame, and used as part of a pumping or graduated dispensing system. The syringe was not intended to be filled and removed, so another syringe could take its place, since the syringe was held in place by a securing clamp.
U.S. Pat. No. 4,187,890 (Paul E. Stach et al) disclosed an apparatus for use in filling small containers, using a pumping syringe during the dispensing process. The pumping syringe was fixed to a bulky framework and had no mobility. If a target syringe was used, as the small container to be filled, the fluid substance was injected into the target syringe, using pressure applied from the pumping syringe.
None of the prior art allows for a hand held unit to operate both as a portable manual single syringe filler and/or dispenser, and a repetitive uniform dosage dispenser. A hand held unit offers convenience of use, and manipulation for obtaining or dispensing medication, which could not be accomplished with a stationary table unit.
The prior inventions lack the ergonomic features, use of air pressure for the drawing and dispensing force, and mobility necessary to fill individual syringes accurately and without stress on the operator. This invention features a frame, which is designed to be held with a neutral wrist posture, and manipulated by the operator during the manual syringe filling process. The use of air pressure to manipulate the syringe results in a smoother operation and less repetitive stress on the operator and mechanical parts during the process. Additionally, the use of pressurized air, or inert gas, does not provide a potential ignition source, as an electrically driven motor system would. Pressurized gas can be tailored to give a specific pushing and pulling force on the syringe plunger, to operate effectively with liquids of varying viscosities.